The present invention relates to an apparatus for detecting the presence of a record medium, and more particularly relates to such an apparatus in which both the presence of the record medium is detected and the speed of motion of the record medium is measured during the passage of the record medium along a feed path (which may be formed by drive belts or rollers).
The apparatus which is the subject of the present invention may be employed in a variety of applications in which it is desired to detect the presence and speed of motion of record media as said media traverse a feed path. One such application is in a printer module which is employed in automated teller machines (ATMs) widely used by financial institutions such as banks. The printer module is capable of printing an account balance or a receipt of an ATM transaction, for a customer who uses the ATM.
The printer module prints, say a transaction receipt, on a continuous roll of paper and cuts the paper to size after the receipt is printed. The receipt is then transported to a receipt slot in the front fascia of the ATM for collection by the user of the ATM.
The continuous roll of receipt paper is mounted on a spindle the ends of which are each received in a recess in the printer. During operation the leading portion of the roll of paper is received by feed means which transport this portion of the paper, extending from the paper roll, through a dot matrix printer which prints text on the paper a dot line at a time, the paper being advanced a predetermined distance between each dot line. Several consecutive dot lines are required to print an alpha numeric character using this method of printing.
One problem with this mechanism is that friction on the aforementioned spindle or partial jamming of the paper can cause the paper to be transported through the printer more slowly than anticipated, resulting in compressed print which in some cases will be illegible. This is a particularly serious problem when the document being printed has legal significance, such as a transaction receipt.